As disclosed in U.S. Pat. No. 6,361,212, a top opening reclosable bag is shown in which fastener strips are sealed on a sheet or web of plastic film in bag-length intervals, the sheet is formed into a tube, sealed along its longitudinal edges. However, an apparatus for sealing the reclosable fasteners is not disclosed. A wide variety of patents are directed to the manufacture of reclosable thermoplastic containers on a form-fill-seal machine. For example, U.S. Pat. Nos. 4,617,683 and 4,655,862, inventor Christoff, are directed to transverse application of fastener profile on a web material for subsequent use on a form-fill-seal machine. Similarly, U.S. Pat. No. 4,709,533, inventor Ausney, is also directed to a method and apparatus for forming a vertical tubular form-fill package. U.S. Pat. No. 4,790,126 is directed to a fill and seal machine for reclosable bags, inventor Boeckman. U.S. Pat. No. 4,909,017, McMahon, is directed to a reclosable bag material and a method and apparatus for manufacturing material and for use in the subsequent form-fill-seal machine.
Also shown in U.S. Pat. No. 6,350,340, inventor James R. Johnson, is a method of manufacturing a web of thermoplastic film having a series of reclosable fasteners disposed thereon on one side. The web with the fasteners thereon is subsequently fed into a form-fill-seal machine, sealed along the longitudinal edges of the film to form a tube, across the open end. The film is then sealed to the back edge of the fastener profile. The film is then cross sealed again to form a sealed package containing product therein.
A continuing problem with the above-listed systems is the coordination of the top seal with the mechanism for sealing the back surface of the fastener profile to the film. In addition, although form-fill-seal machines are widely used, the addition of fastener profiles thereon requires the addition and installation of complex equipment which is relatively difficult to adjust.
Accordingly, it is an object of the present invention to provide an apparatus for cross-sealing tubes of thermoplastic film having a series of reclosable fastener profiles sealed thereon and to provide an apparatus for sealing the back edges of the fastener profile to the film, all in a modular system.
It is an additional object of the present invention to provide such an apparatus that can be used for sealing top and bottom seals sequentially on a form-fill-seal machine.
An additional object of the present invention is to provide a seal configuration for top opening containers which provides air-tight seal of the reclosable fasteners to the film while not sealing the opposing sides of the tube of plastic film together.